The throughput of a parallel distribution processing executed by parallel computer may be enhanced by improving the communication efficiency in the parallel computer through an optimization of a connection form of a server and a switch (i.e., network topology) in the parallel computer. In addition, when a large number of servers are connected with a small number of switches by an optimization of the network topology in the parallel computers, construction cost of the parallel computers may be suppressed.
A network topology called a Latin square fat tree is disclosed in a technical journal. The Latin square fat tree has a feature that there is only one route through a spine switch between two predetermined different leaf switches. Using the Latin square fat tree, it is possible to connect more servers with the same number of switches as compared to a common two-stage fat tree.
In the parallel computer, a collective communication called all-reduce communication is often executed. The all-reduce communication refers to a communication in which all target nodes hold the result of an operation executed using data possessed by all of the target nodes, and the name of all-reduce refers to an operation thereof. When the all-reduce can be executed by some servers in a system adopting the Latin square fat tree (hereinafter, referred to as a Latin square fat tree system), other collective communication, etc. can be executed with respect to servers other than the some servers.
Related technologies are disclosed in, for example, M. Valerio, L. E. Moser and P. M. Melliar-Smith, “Recursively Scalable Fat-Trees as Interconnection Networks”, IEEE 13th Annual International Phoenix Conference on Computers and Communications, 1994.